The Doomsday Clock, a metaphorical measure of how close humanity is to imminent disaster, jumped to two-and-a-half minutes to midnight today, the closest it's ever been since the height of the Cold War. The Bulletin of the Atomic Scientists, the anti-nuclear weapons group that first set the clock in 1947, said that the reason for the time change is simple: Donald Trump.
Explaining its members' reasoning, the Bulletin cited the continued threats posed by nuclear weapons and climate change as well as a new one that could make them worse: "a rise in strident nationalism worldwide in 2016, including in a US presidential campaign during which the eventual victor, Donald Trump, made disturbing comments about the use and proliferation of nuclear weapons and expressed disbelief in the overwhelming scientific consensus on climate change."
Prior to today's change, the Doomsday Clock was set at three minutes to midnight. It was also set at three minutes from midnight in 1947 and 1984. Today's setting is the closest to midnight since 1952, when the United States and the Soviet Union tested the first hydrogen bombs. The furthest the clock has ever been from midnight was 17 minutes, in 1991, after the Cold War had ended and both the United States and Russia were reducing their nuclear arsenals.
Here's Bulletin's full statement for why its members are alarmed by the election of President Trump: